Method for setting gypsum utilizing retarder

Abstract

A process for setting gypsum which comprises incorporating carboxyalkylated protein as a setting retarder in gypsum paste in an amount of 0.001 to 5% by weight based upon the weight of the gypsum.

What is claimed is: 
     
       1. An improved process for setting gypsum wherein water is admixed with gypsum to form a gypsum paste which then sets, the improvement comprising admixing a carboxylated protein in said gypsum paste in an amount of from 0.001 to 5% by weight based upon the weight of the gypsum, whereby the setting time of said gypsum is retarded. 
     
     
       2. The process of claim 1, wherein the carboxyalkylated protein has a carboxyalkyl group content of from 0.1 to 30% by weight based upon the total weight of the carboxyalkylated protein. 
     
     
       3. The process of claim 2, wherein the alkyl moiety of the carboxyalkylated protein has from 2 to 8 carbon atoms. 
     
     
       4. The process of claim 3, wherein the carboxyalkylated protein is a carboxyethylated protein. 
     
     
       5. The process of claim 3, wherein the carboxyalkylated protein is prepared by contacting a protein with acrylonitrile in the presence of an alkali and hydrolyzing the resulting reaction product. 
     
     
       6. The process of claim 3, wherein the carboxyalkylated protein is prepared by contacting a protein with an α,β-unsaturated aliphatic acid or a salt thereof under neutral or alkaline conditions. 
     
     
       7. The process of claim 3, wherein the carboxyalkylated protein is prepared by contacting a protein with an α,β-unsaturated aliphatic acid ester under neutral or alkaline conditions, and hydrolyzing the resulting reaction product. 
     
     
       8. The composition of claim 6, wherein the α,β-unsaturated aliphatic acid is acrylic acid. 
     
     
       9. The process of claim 1, wherein the protein is at least one material selected from the group consisting of a microorganism and a protein extracted therefrom, collagen, gelatin, glue, keratin, casein, egg albumin, soybean protein, wheat gluten, and a hydrolyzed product thereof. 
     
     
       10. The process of claim 1, wherein the carboxyalkylated protein is a carboxyethylated protein. 
     
     
       11. The process of claim 1, wherein the protein is at least one material selected from the group consisting of a microorganism and a protein extracted therefrom, collagen, gelatin, glue, keratin, casein, egg albumin, soybean protein, wheat gluten, and a hydrolyzed product thereof. 
     
     
       12. The process of claim 1, wherein the alkyl moiety of the carboxyalkylated protein has from 2 to 8 carbon atoms. 
     
     
       13. The process of claim 1, wherein said protein is in an amount of from 0.01 to 1% by weight based upon the weight of the gypsum. 
     
     
       14. The process of claim 13, wherein said carboxyalkylated protein is a carboxyethylated protein, and wherein said protein has a carboxyethyl group content of from 0.1 to 30% by weight based upon the total weight of the carboxyalkylated protein. 
     
     
       15. The process of claim 14, wherein the protein is at least one material selected from the group consisting of a microorganism and a protein extracted therefrom, collagin, gelatin, glue, keratin, casein, egg albumin, soybean protein, wheat gluten, and a hydrolyzed product thereof. 
     
     
       16. The process of claim 15, wherein the carboxyalkylated protein is prepared by contacting a protein with acrylonitrile in the presence of an alkali and hydrolyzing the resulting reaction product. 
     
     
       17. The process of claim 15, wherein the carboxyalkylated protein is prepared by contacting a protein with an α,β-unsaturated aliphatic acid ester under neutral or alkaline conditions, and hydrolyzing the resulting reaction product. 
     
     
       18. The process of claim 15, wherein the carboxyalkylated protein is prepared by contacting a protein with an α,β-unsaturated aliphatic acid or a salt thereof under neutral or alkaline conditions. 
     
     
       19. The process of claim 18, wherein the α,β-unsaturated aliphatic acid is acrylic acid.